THE thermionic valve has long been recognized as a useful tool in many branches of science and engineering; but few, with the exception of experimenters, have realized that it can be usefully applied ...

The question, “Presta or Schrader?”, may seem confusing when you’re new to cycling and head to a bike shop to buy a replacement inner tube. For the vast majority of bikes, there are two types of valve ...

(Reuters Health) - People who need a heart valve replaced often face a dilemma: should they have a mechanical valve made of graphite or a biological valve derived from a cow or pig? A new study ...